Rebuilding my rear drums

[kennygunit 10]

Hello,

 

On Friday, i am going to be rebuilding my rear drum brakes for my 1969 coupe. The car was originally 4 drum brakes, but sometime during its life, the fronts were converted to disk. The reason why i am rebuilding my rear is because i have a leak in my rear drum brake cylinders. Before i get started, i just had some questions.

 

1) How do i tell what size brake shoes i need? (completely stock drums, i've never changed the shoes while owning the car (2-3 years).

 

2) What advice do you have for someone whos never rebuilt drum brakes? (i'm def. above average with mechanic work, going to be my future career)

 

3) Whats the process for bleeding drum brakes (doing it by myself, and with another person)

 

Thanks guys!

[RogerC 136]

1 You'll probably have to state V8 or 6 cylinder. My 69 has a 9" rear from a cougar XR7 but uses my original drum setup so I'm thinking there was only one size for V8 cars.

 

2 Lay out your old parts as assembled as you remove them and do one side at a time. It helps when putting the new parts on as spring position can get confusing.

 

3 After brakes are re-assembled, with drums of course, fill reservoir, pump peddle, hold peddle down on last stroke, loosen bleeder screw slightly and retighten before releasing peddle. Repeat till no more air comes out of the screw. Start with the wheel cylinder farthest away from the master cylinder.

Edited March 31, 2011 by RacerX

[DRASTiK 22]

RacerX made some excellent points. Especially the part about doing one side at a time. You don't want to take them both apart and then get confused with which spring goes where. You can use the assembled side as a diagram while putting the other together.

Couple of other things you should know.

1. DO NOT press the brake pedal while any of drums are off of the car.

2. Regarding the bleeding process, do as RacerX suggested. It will require two people unless you want to go and purchase some extra tools. If a helper is not an option, you can gravity bleed them and you'll probably be able to get the air out of them. Gravity bleeding is done by filling the reservior and leave the cap off of it. Then loosening the bleeder on one of the brakes. I'd do the passenger side rear first. You should see brake fluid begin to drip out of the bleeder valve. Let it drip for a minute or so and then close it. Then open the bleeder on the driver-side rear and repeat the procedure. Then top off the reservior and place the cap on it. Check the brake pedal to ensure it's not going to the floor (which would indicate that there's air in it. After pumping the pedal a few times, it should harden up.

[stangs-R-me 120]

There is also the possibilty that your brakes are not assembled correctly now !!

 

Friend just bought a '70 Mach 1 and had a wheel cylinder leak on the rear pass side. Took it appart and it was missing the parking brake lever, cross link, closs link spring & plate as well as the little cable that goes around the back side from the star adjuster up to the upper anchor pin !!

 

Then while trying to replace the wheel cylinder noticed bleeder & tube connection were oposite. Brought both wheel cyl's. back to the store and they did give him the correct "RIGHT" side cylinder however a previous owner had put a LEFT side one on. Not wanting to mess with the line, he ended up putting a new left cyl back on. Left side has the correct cylinder but was also missing the parking brake hardware but did have the cable but it was freyed and ready to break.

 

Hopefully you've got Parking Brake levers as only one side is still available NEW and the other is now obsolete.

 

I've attached a Drum Brake Diagram I scanned out of my old Chilton book that may help too.

 

Doug

[JoeyS 12]

I am also rebuilding my rear drum brakes. I measured the brake drum and shoes to find the right size. My drum was 10" across on the inside and the shoes were 1.75" wide. 10 x 1.75

 

Take lots of photos with a digital camera to help with reassembly. I can never remember exactly how things go back together so I have to refer back to the pictures. Shoot a few more pictures than you think you need.

 

I purchased a brake rebuild kit that included all the springs needed for the rebuild. It included two curved washers, one for each side. Could someone tell me where these go? I couldn't find any reference to them and never saw these on the original brake set up.

 

The diagram posted earlier is of the right side brakes. To simplify things it might be easier to start on that side (passenger side), otherwise everything is a mirror image.

 

Good luck on your brake rebuild.

Joe

[foothilltom 33]

+1 on taking pictures during disassembly! It's easy to get confused which shoe goes where as they are different depending on the left or right side of the car. In other words, don't just take a picture of one side. Do one side at a time like the fellers have said here.

 

And if you don't have one, do yourself a favor and invest in the hand tool to remove and replace those small springs. It will safe you some heartache. I also bought the "brake spoon" (or whatever its called) to remove the long spring at the top but later realized I could have used a number of normal tools for that.

 

You can do this. I'm about a 3 out of 10 on the mechanically inclined scale and I did it!

[stangs-R-me 120]

I purchased a brake rebuild kit that included all the springs needed for the rebuild. It included two curved washers, one for each side. Could someone tell me where these go? Joe

 

I think those go between the parking brake actuator lever and the back side of the shoe.

 

Doug

[kennygunit 10]

Just letting everyone know, the brake job was a success! The car stops way better than before.

 

Only question i have for you guys is, how do i find the right spot for where the brakes should be adjusted? I know you turn the star screw through the backing plate, but i just don't know where it should be set at.

 

Thanks again for everyones help!

[6T9Mach1 12]

I found it helpful to find a picture of a rebuilt drum brake on the internet; one that uses the correct rebuild kit with the colored springs if you have a kit with colored springs. My Mustang was the first car I rebuilt drum brakes on and did not find the process to be too difficult.

[RogerC 136]

Just letting everyone know, the brake job was a success! The car stops way better than before.

 

Only question i have for you guys is, how do i find the right spot for where the brakes should be adjusted? I know you turn the star screw through the backing plate, but i just don't know where it should be set at.

 

Thanks again for everyones help!

 

After re-installing the drums you want to make an initial adjustment by turning the star screw till the drum gets tight as you try to rotate it then back it off again till you feel a slight drag on the drum. That is all you need to do as, once you start driving, the self adjusting feature will keep it adjusted correctly provided everything was assembled correctly and is functioning properly. If you didn't do the initial adjustment, new shoes are usually close enough to the drums they'll stop you ok and after several stops the self adjusting feature will bring it into proper adjustment. I always drive back and forth in the driveway some after a brake job to ensure the shoes have adjusted themselves before hitting the road.

Edited April 2, 2011 by RacerX
added more info

[foothilltom 33]

Hey RacerX, is it your recollection that the "self adjusting" feature only works when you stop while moving backward? I read somewhere that -- after making the adjustment that you already described -- you accelerate and stop quickly in reverse for the auto-adjust. Maybe it works both ways? Just curious.

[RogerC 136]

Hey RacerX, is it your recollection that the "self adjusting" feature only works when you stop while moving backward? I read somewhere that -- after making the adjustment that you already described -- you accelerate and stop quickly in reverse for the auto-adjust.

 

It seems to me that's how it works but I wasn't sure.